The objective of this study was to investigate drivers’ behavior, including traffic speed and vehicle lateral
placement, as well as accidents at interchange loops. Twenty seven loops located in rural and suburban areas
were investigated. For different vehicle classes, loops were evaluated using four measures; speed profile, speed
consistency, vehicle lateral placement and traffic accidents. Data on loop characteristics, traffic speed and
lateral placement of vehicles was obtained through field measurements.
Analysis results revealed that entrance, exit and the middle part of the loop are critical locations. Loop entrance
and exit exhibited speed inconsistency and experienced a large number of collision accidents. The use of
circular curve with a radius of more than 70 m may eliminate this problem. At the middle part of the loop,
vehicles were found to get closer to the inner edge of the pavement and this location experienced considerable
loss-of-control accidents. Results also indicated that passenger car is the critical vehicle for a consistent design.
معالي الأستاذ الدكتور محمد طالب عبيدات | HE PROF. Moh’d Taleb Obaidat | 5055